Columbretes

“All of the islands contain the same geognostic elements. Specifically, they are all volcanic, similar to tuff in terms of the shape of their strata, or with slightly sloping layers, crowned by a thick deposit of blackish cellular basalt, which seems to have originated from a current of lava that once filled the crater. This crater—which, during the eruption, had been a complete cone—represents just two thirds of the circumference that was destroyed by the action of the sea on its most exposed face, the north-northeast face.”

Urios, G., Nachtwey, J., Translation, Columbretes, 1895, Castellón City Council, 1990.